Bridge pontic



' June 16, 1936. "J. R. SCHWARTZ BRIDGE FONT I C Filed June 14, 1934 ATTORNEY Patented June 16, 1936 PATENT OFFICE 2,044,106 BRIDGE PoN'rio Jacob R. Schwartz, Brooklyn, N. Y. Application June 14, 1934, Serial No. 730,569

' 1 Claim.

My present invention relates to dental bridgework, and more particularly to an improved type of dental bridge pontic.

In dental bridgework, the parts to be restored are the lost teeth, and the restoration units are referred to as pontics. A true restoration should be true from all aspects, such as the surgical, the engineering, the artistic and in the workmanship. While it is true that at the present time a wide variety of pontics are available to the dentist, yet it cannot be stated that such pontics lend themselves to the production of true restorations.

It may be stated that it is one of the main objects of my present invention to provide a tooth form construction such that it is admirably adapted for use as a bridge pontic, the construction not only avoiding excessive bulk on the lingual surface of the tooth form, but, additionally, preventing fulcrum, or rotational, fracture of the restoration during use of the bridge.

Another important object of the invention is to provide a bridge pontic which includes a backing having essentially two spaced anchoring posts adapted to be inserted in complementary recesses in the lingual surface of the tooth form, this pon tic construction providing a double anchorage to prevent fracture of the tooth form when in use; the angular relation between the backing and the anchor posts beingsuch as to permit easy replacement of the tooth form when necessary.

Another object of the invention is to provide a pontic construction wherein the tooth form has lingual bevels and the retention backing is provided with edges adapted to cooperate with the lingual bevels to protect the edges of the tooth form, and, also, provide an anatomically true tooth shape.

Still other objects of the invention are to improve generally the efliciency of bridge pontics; and to particularly provide a pontic construction which is not only durable and reliable in usage, but economically constructed and assembled in a bridge. l

The novel features which I believe to be characteristic of my invention are set forth in particularity in the appendedclaim, the invention itself, however, as to both its organization and method of operation will best be understood by reference to the following description taken in connection with the drawing in which I have indicated diagrammatically several constructions whereby my invention may be carried into effect.

In the drawing:

Fig. 1 shows a side view of a tooth form embodying my invention,

Fig. 2 is an isometric view of the form shown in Fig. 1,

Fig. 3 is an isometric view of a retention backing complementary to the form in Fig. 2,

Fig. 4 shows a sectional view through an assembled tooth form and backing,

Fig. 5 is a sectional view taken along a vertical median through the backing in Fig. 3, 10

Fig. 6 shows the lingual surface of the tooth form in elevation,

Fig. 7 is a side View of a restoration embodying the present invention,

Fig. 8 shows in isometric a backing for a tooth form embodying a modified form of the invention.

Referring now to the accompanying drawing, wherein like reference characters in the different figures correspond to similar constructional elements, the tooth form I is composed of porcelain, and is provided with a metallic backing 2. The form and backing are complementary, and when united provide a pontic for a bridge. The tooth form may, of course, be composed of materials other than porcelaim'the backing may be fabricated from a gold alloy. As is well known to those skilled in the dental art, the direct contact between the tooth form and the gum tissues takes place at the ridge, or saddle portion, 3 of the form. In Fig. '7 is shown the gum 4 in operative relation to the porcelain surface of the ridge 3.

While the present invention is to be described in connection with a single tooth form and backing, it is to be clearly understood that the invention is not so limited. The numeral 2 is to be understood as designating a single backing or a gang of backings. In actual practice the backings 2 are permanently aflixed, or anchored, between the spaced anchor teeth, and the tooth forms are secured to the backings; the assembled unit having the appearance shown in Fig. 7.

Fixed restorations in the form of porcelain pontics have been known; however, the pontics used heretofore are all subject to disadvantages in actual usage. In most pontic constructions known in the prior art a retention member is provided on the backing, while a cooperating recess is provided in the tooth form. These prior constructions are such that excessive bulk cannot be avoided on the lingual aspect of the form when completing the tooth form as a bridge pontic. Again, such earlier forms have been subject to fracturing. Additionally, they have not been 55 constructed to protect the lingual edges of the tooth form against chipping.

The tooth form and backing of the present invention are constructed to avoid these disadvantages noted heretofore. The backing 2 (Fig. 3) has the configuration shown, and is provided with an upwardly inclined cylindrical anchor post 5. The numeral 6 designates a second anchoring member which is spaced from post 5. The member 5 is of a substantially rectangular configuration; its ends being arcuate. A reinforcing rib I connects the post 5 to the member 6. The post 5, rib I and horizontal member 6 are preferably integral with the backing 2, and are located at sub stantially the middle third of the backing.

The lingual side 3 of the tooth form is provided with three recesses to receive the retention elements of the backing. The upwardly inclined post hole 8 is cylindrical in configuration, and is of a length and diameter to receive the entire post 5. The entrance to recess 8 is located in the gingival third of the lingual surface of form I. The rib I registers with a channel recess 9, the latter connecting the entrance of post hole 8 to the substantially rectangular slot, or recess, II). The recesses 9 and III are designed to receive rib 5 and member 6. The recesses 9 and ID are located in the middle third of the lingual surface of formI.

The lingual surface of the tooth form is provided with bevelled edges II, I2 and I3; the incisal edge of the tooth form being especially protected because of this construction. The gingival third of the lingual surface of the tooth form is denoted by the numeral I4, and, as shown clearly in Figs. 2 and 6, is provided with an edge I4 merging into edges II and I3; the lingual face I5 thereof is inclined at an angle to face 3.

The backing 2 is given a configuration so that it complements the lingual shape of the tooth form. Thus, and as shown in Fig. 3, the protective edges I2, II, I3 and I4 are adapted to contact the edges I2, II, I3 and I4 respectively when the form and backing are assembled. The face I5 is adapted to contact with the inclined surface IS; the post 5 projects from the lower edge of surface IS. The appearance of the assembled pontic is shown in Fig. 7. It will be noted that the lingual aspect of the pontic shows no excessive bulk at the gingival third. Furthermore, it will be seen that (as shown in Figs. 4 and 7) the lingual edges of the tooth form are protected; and that they are of normal appearance at the lines of contact of the form and backing.

When the tooth form is to be secured to the backing, and assuming the backing in fixed position in the mouth, it is only necessary to provide the cement on the contact edges and retention devices. The form is then slid downwards upon the post 5, until the latter, rib I and anchor 6 are all disposed in recesses 8, 9 and I0 respectively. Excessive bulk and clumsy finishing operations are avoided by this construction. The spaced post 5 and member 5 provide security against fracture of the tooth form. The transverse anchor post 6 prevents fulcrum fracture as well as rotational fracture.

The strengthening rib I, between the double anchorage members 5 and 6, greatly improves the bond between the tooth form and backing. Of course, the double anchorage may be modified. For example, the transverse member 6 may project beyond the rib I so that the exposed faces of member 6 and rib I are not in a common plane. In that case the slot I0 would have to be correspondingly deeper. The post 5 need not have a circular section; it may be polygonal, or it may even be serrated on its outer surface to better grip the surface of bore 8.

In Fig. 8 is shown a modification of the backing 2. .The rib I is cylindrical in contour. The member 6 has been replaced by a cylindrical post 6' parallel to post 5, but of a lesser length. The recesses in the lingual surface of the tooth form would be shaped to register with these retention elements. As in the case of the backing shown in Fig. 3, from a generic viewpoint the retention means on the backing comprises a pair of spaced anchorage posts adapted to register with corresponding recesses in the lingual surface of the tooth form.

While I have indicated and described several constructions for carrying my invention into effect, it will be apparent to one skilled in the art that my invention is by no means limited to the particular constructions shown and described, but that many modifications may be made without departing from the scope of my invention, as

set forth in the appended claim.

What I claim is:--

An artificial tooth comprising a backing and a tooth form, said form being provided with a pair of spaced recesses in its lingual surface at substantially the middle third thereof, one of the recesses being a substantially cylindrical bore located above the other recess and sloping upwardly toward the ridge saddle portion of the form, the bore extending deep into the body of the form, the other recess having a substantially rectangular configuration and being arranged transversely of the cylindrical bore, a vertical channel connecting the transverse recess and cylindrical bore, the channel and transverse recess having substantially the same depth and being relatively shallow with respect to the said bore,,said backing being provided with an upwardly sloping post of a length substantially equal to that of the bore depth, a member arranged transversely of said backing and having a configuration substantially that of the transverse recess, and a vertical rib on the backing having thickness substantially equal to that of the channel, the vertical, incisal and gingival edges of the lingual surface of the form being bevelled, said backing being provided with protective edges projecting a sufiicient distance from the backing face to completely contact with said bevelled edges, said transverse member and vertical rib projecting from said backing a distance substantially equal to the projection distance of said protective edges, and said post, transverse member and rib being adapted to register with the bore, transverse recess and channel respectively when said form is united with the backing. I

JACOB R. SCHWARTZ. 

